1. Field of the Invention
This invention relates to an improved throttle valve assembly for an internal combustion engine in a motor vehicle.
2. Description of the Prior Art
In modern internal combustion engines used in motor vehicles, a throttle device is employed, which as a rule, is produced as a circular butterfly valve, is contained in the intake section of the engine, and meters the volumetric flow of fresh air to be taken in that is required for the combustion. Due to the high flow velocities of the residual air flow in the intake section and at low outside temperatures, the H2O contained in the fresh air can condense on the wall of the tube; with further cooling, ice can form inside the fresh air line, which can considerably impair the smooth functioning of the throttle valve. Furthermore, in multi-part throttle plate housings, care must be taken that in the region of the dividing joints of the housing halves, no outside air can enter into the intake section downstream of the throttle valve on the side oriented toward the internal combustion engine.
DE 33 46 167 A1 relates to a throttle valve fitting in which a throttle valve is disposed on a shaft, which in turn can be affixed in the fitting housing at both ends by means of slide bearings. These slide bearings are each press-fitted into a shaft bore and have end surfaces oriented toward the throttle valve, which are curved to correspond with a wall of housing bore and constitute a part of this wall. This embodiment of the slide bearings results in an extremely low leakage rate of this throttle valve fitting.
DE 198 43 771 A1 relates to an electromotive actuator, in particular with a throttle valve. This reference discloses an electromotive actuator with a housing and an electric motor, which is disposed on a drive side inside the housing and is for driving a movable element disposed in the housing. In particular, this movable element is a throttle valve and a separate electronic housing for containing control and/or evaluation electronics can be fastened to the housing. On the one hand, this particularly permits electromagnetic interference irradiations to be prevented and on the other hand, mass-produced electronic actuators, which do not require a control unit, can continue to be used without requiring changes in the form for the production of the actuator.
DE 29 49 041 B1 has disclosed a heating system for mixture preparation in mixture producers. According to this embodiment, this is a heating system for mixture preparation in the mixture producers of internal combustion engines, with a tube wall that defines a main flow, a main throttle element downstream, and a fuel metering device in the upstream part of a mixing chamber. Over a part of its longitudinal span, this mixing chamber is embodied as a heat exchanger double wall with an annular hot water chamber, which has a water inlet fitting at its one end and a water outlet fitting at its other end. The heat exchanger can be connected to a cooling water circuit by means of a thermally controlled connecting valve that opens when higher temperatures are reached. The heat exchanger is disposed above the cooling water level when the connecting valve is closed and when the cooling water circuit is switched off. The inner wall of the heat exchanger, which adjoins the main flow path of the mixture producer, is comprised of an electrical heating resistance material and is electrically connected to a voltage source by means of an electrical switching element, which is thermally controlled as a function of the cooling water temperature and opens when a particular higher water temperature is reached.
DE 101 14 221.8-13 has disclosed a heatable throttle device for internal combustion engines. In this device, a fluid flow passes through a flow cross section of a bore, and a fluid flow can be metered by means of an actuatable throttle element that can pivot in a receiving bore in the housing. Between a wall of the bore and the outer circumference of the housing, the housing contains cavities for a heating or cooling medium.
The advantages of the present invention can be seen primarily in the fact that now, with a single insert element, which is disposed between the housing halves of a throttle housing comprised of a top shell and a bottom shell, the housing element is, on the one hand, sealed to prevent the intake of external air while on the other hand, the insert element provides a compensation for tolerances in the dividing joints of the two housing halves of the throttle housing, which is embodied, for example, as an injection molded or a diecast aluminum component. This permits finishing procedures, which are usually executed in the course of machining, to be eliminated when assembling the housing halves of the throttle valve housing. The insert element incorporated into the dividing joint of the two housing halves can also seal a heating system integrated into the throttle valve housing. For example, if cavities are integrated into the walls of the throttle valve housing halves, through which a heating medium flows, then the insert element can effectively perform the function of sealing these cavities. In addition, the insert element can compensate for diameter differences in the flow cross section of the throttle valve housing halves so that no abrupt diameter changes and therefore no eddy zones are produced in which mediums contained in the intake air can collect over the operating time of the internal combustion engine.
On the one hand, the insert element can be embodied as a prefabricated shaped part, with a conically extending inner wall; on the other hand, it can also be made of a hardening material so that after assembly, the two throttle valve housing halves are fixed in place for subsequent operation. Both the embodiment of the sealing element as a prefabricated, pre-formed elastomer ring and the embodiment of the sealing element as being made out of a formable material that hardens after being processed permit the compensation of manufacturing inaccuracies on the end surfaces of the upper and lower throttle valve housing halves to be assembled. Up until now, a compensation of manufacturing inaccuracies such as out-of-round errors and balance anomalies was only possible through a complex and expensive finishing of the throttle valve halves to be assembled, usually by means of machining.
The sealing element, which is embodied as an elastomer insert ring or as a hardening molding compound, with a corresponding shaping of the wall of the sealing element oriented toward the flow cross section, and in particular an angled outlet that is formed onto it, can achieve an improved flow guidance in the flow direction of the intake air flow in the intake line of the intake section of an internal combustion engine.